High-pressure indicator



(No Model.)

A. T. WILLARD.

HIGH PRESSURE INDICATOR. No. 318,152. Patented May 19, 1885.

TMITNISSES I g 0, OW W FWZ/LYWM UNITED STATES PATENT OFFICE.

ALEXANDER T. WILLARD, OF CHELSEA, MASSACHUSETTS.

HIGH-PRESSURE INDICATOR.

SPECIFICATION forming part of Letters Patent No. 318,152, dated May 19,1885.

' Application filed May 29, 1884. (No model.)

To aZZ whom it may concern:

Be it known that I, ALEXANDER T. WIL- LARD, of Chelsea, in the county ofSuffolk and State of Massachusetts, have invented a new and usefulImprovementin High-Pressure Indicators,which will, in connection withthe ac companying drawing, be hereinafter fully described, andspecifically defined in the appended claims.

This invention has for its object the providing of an accurate, durable,and low-cost gage or indicator adapted to indicate the pressure of steamor fluids in confined space; and it will, in connection with theaccompanying drawing, be hereinafter more particularly and 'fullydescribed and claimed.

In said drawing my invention is shown in sectional elevation, in whichor represents a cylinder having a screw-threaded shank, 12,

adapted to be secured in a steam-chest or other body in which isconfined steam, water, or other fluid under pressure. An axial passageextends through said cylinder, and being of a greater diameter in itsupper section and of a lesser diameter in its lower section a shoulder,c, is thereby produced. A piston-rod or plunger, d, is arranged to slideloosely and freely in cylinder a, and is pro vided or formed with acollar, j, which, by

engaging shoulder a in the cylinder, determines the descent of theplunger. A helical spring, 6, is arranged on plunger (2 above its collarj. A cap, f, is screw-threaded on the top of the cylinder, and betweensaid cap and the end face of the cylinder is arranged the ring-packingg,which renders steam-tight the joint between plunger d and said cap. Aproperly-spaced and numbered scale or tablet, h, is secured to andsupported by rod t, secured in cap f.

In practical operation, when cylinder at is secured in the top of anyreceptacle in which steam or any fluid or liquid is confined underpressure, such pressure will be exerted upon plunger (1 in the ratio ofthe area of its crosssection, which will force it upward, therebycompressing spring 6, which latter exerts its force between collar j andpacking 9. As the plunger rises it indicates the pressure exerted uponit by the relation of its upper end to the marks and figures on tableth, and when the pressure upon the plunger abates spring 6 forces itcorrespondingly downward.

I am aware that it is old, common, and well known to employ for thepurpose described a cylinder, a piston-rod, with a piston thereon,fitting the bore of the cylinder closely, a spring on the plunger, andan indicating scale or tablet, upon which the plunger indicates thepressure; but my invention differs therefrom, in that I employ no pistonas such, the steam acting on the lower end of the plunger only, and Ifreely admit the steam into the cylinder in its entire length byarranging my packing-joint at the top, thereofiwhereby I also reduce theconsequent friction to the least possible amount, and the force of thespring exerted upon the packing presses the latter against the rod.lVhile in said older device the piston must be of a diameter greaterthan the coiled spring, in order that the latter may move freely in thebore of the cylinder, and the friction resulting from the close fittingof the piston in the cylinder is of such degree as to require a springof such great strength in order to properly resist the steam-pressureand depress the plunger, that the device must lack the requisitesensitiveness to properly indicate the actual pressure to which thepiston is being subjected. If desired, a differentiated indicator may bearranged in any of the wellknown methods, whereby the lesser movement ofthe plunger will move an indicating finger through an augmented spaceover the tablet.

My invention is of great utility in connection with vulcanizing-boxesfor dental purposes, where it has been thoroughly tested, as it isinexpensive, indestructible by proper use,

and is compact in size, and always reliable in its action.

I claim as my invention The combination of cylinder a, having shoulder0, formed by the larger and smaller bore therein, plunger d, fittingloosely in the smaller bore in said cylinder and provided with collar3', to be engaged by said shoulder, cap f, packing g, and spring 0,arranged on said plunger between shoulder c and said packing,substantially as specified.

T. W. PORTER, EUGENE HUMPIIREY.

